


Collar

by MageOfLight



Series: Kustard Dom/Sub-verse [4]
Category: Undertale
Genre: M/M, Red's a mushy sob when ya think about it, back story and explination for Underfell monsters wearing collars, past Edge/Red, sugar sweet nonsense
Language: English
Status: Completed
Published: 2017-12-18
Updated: 2017-12-22
Packaged: 2019-02-16 17:35:46
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 2,291
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13058838
Author URL: https://archiveofourown.org/users/MageOfLight/pseuds/MageOfLight
Summary: A background story for Red and Edge's former relationship, as well as explaining how collaring works for Underfell monsters and what collaring another monster means. Some of this won't make a heck of a lot of sense without reading the previous parts of the series.





	1. Chapter 1

Sans was 15 when Papyrus first tried gifting him a collar, the 10-year-old promising to always protect him. Sans laughed that first attempt off, though he kept the sloppily made ring of fabric and weaved grasses.  
  
The second attempt was shortly after they lost Gaster, Papyrus knowing something was _wrong_ but not knowing what. Papyrus was only 14, though, and Sans still felt it was his job to protect Papyrus, not the other way around. Still, he never attempted to collar Papyrus like Papyrus was attempting to do for him. Sans did not make promises he wasn't sure he could keep, after all. He still kept the second attempt, though.  
  
There's a saying, 'third times the charm'. The third and final attempt for Papyrus to collar Sans came when Papyrus was 18. He'd just started training with Undyne to become a member of the Royal Guard. The young Captain had taken a liking to him right away and was working him hard, though Papyrus enjoyed it.  
  
Sans had gotten a job as a sentry so he could keep an eye on his baby brother easier. It was because of his focus on Papyrus that he didn't see the attack coming until it was too late. The human with the orange soul nearly knocked his head straight off his shoulders as a result of his distraction, but Papyrus had seen them just in time and impaled the human on what was probably 50 or so bone spears. The incident shook Sans to the core and when Papyrus came to him the next day with a finely crafted leather collar, Sans wordlessly lifted his chin, allowing the pleased newly appointed Royal Guard to collar him.  
  
After the collar was in place, the attitude towards him shifted. No one looked at him like they were watching for the moment he let his guard down. Snowdin and Waterfall monsters became more easy going and while he wouldn't ever call them friends, they were the closest thing to that.  
  
His relationship with Papyrus shifted, too. He and his brother became closer, eventually culminating in a loving relationship. And Sans did. He loved his brother beyond anything. He willingly submitted to Papyrus' care, though he never did stop playing pranks on the taller skeleton.  
  
All things change and come to an end, though. Gradually, the nature of their relationship shifted and changed. Flowey messed with time in an effort to help the Underground, but Sans remembered each jump. He became despondent and Papyrus couldn't do anything but watch his brother sink far too quickly into a depressive fugue. It threw a wrench into their relationship, though Papyrus always made good on his vow to keep Sans safe.  
  
Flowey's messing around with time stopped, and the last human came. They were a tiny slip of a thing, and Sans could have easily taken them out even with his joy buzzer in the hand trick if he amped up the electricity it produced a little... but he'd promised the lady behind the door to make sure they got through the underground alive, and Sans never broke his promises.  
  
Sure they did die multiple times and Sans felt guilty for it every time, but in the end, they made it and Sans watched them flee with the tyrant's soul. The queen appeared not long after and took the throne, eventually beginning to wrangle the Underground into shape...  
  
And then time reset. Queen Toriel was extracting the promise from him again. The human emerged from the ruins, and this time, Sans was able to keep his promise with no problems. In the end, the tyrant's life was ended not by the human's hand, but by Sans' magic and Karmic poisoning. Frisk, with help from their small flower friend, broke the barrier and freed monsterkind, leading them out into the sun... and into an alternate universe, apparently.  
  
Sans was astonished to find an already long established monster-made city at the base of the mountain. They were a friendly bunch but outnumbered the monsters from Sans' Underground nearly three to one with their current population. Sans and Papyrus met their alternate selves, and it was quickly decided that they would take nicknames. Sans became Red, and Papyrus became Edge.  
  
Sans and Papyrus invited Red and Edge to stay with them, but Edge declined. After so long of being trapped, Edge couldn't bare to stay in one place. He applied to become one of the Frisk duo's bodyguards and as Captain Undyne's second in command and with their Frisk's endorsement, he was accepted without question.  
  
Before he left on his first ambassadorial trip, Edge pulled Red aside and ended their relationship. It hurt, but Red understood. He'd always love Edge of course, but he'd known the relationship had been over for a long time. This was just putting it to word and making it official.  
  
Time passed and Red and Sans got closer. They started a weird, but comfortable relationship. Technically, it was a 'friends with benefits' situation, but Red didn't think fwbs were... quite like this. They sunk into dominant and submissive roles, Sans for some reason that Red could not comprehend, actually trusting him explicitly. It was thrilling, having total control over someone and knowing that they trusted you to never harm them.  
  
And Red made it a goal to protect Sans. Together, they pulled out of the rut they'd sunk into in the Underground, pulling each other up out of their respective pits until their younger brothers could see the recovery for what it was. They were good for each other.  
  
It wasn't until Red found himself in a fabric store, staring at a wall of coloured leather and trying to decide between crimson or pale blue that he realized that he'd actually fallen in love with Sans. He went home empty-handed that night, and for the first time since being collared by his brother, removed the collar without the intent to ever put it back on. The collar was tucked neatly into the box with the first two attempts, evidence that Edge had always and would always love Red... but that time of their lives was over, and it was time to move on.

\--------------------------------------------

"...hey, sans...?"  
  
"mm? what's up?" Sans looked up at his partner from where he was lounging on the couch, watching TV. Red looked and sounded incredibly nervous, so Sans sat up, flicking off the TV, giving his mate his undivided attention, which Red appeared to appreciate.  
  
"so..." Red paused, muttering what was probably a curse under his breath before crossing the room and flopping on the couch with a nervously agitated air about him. Sans waited silently, not encouraging Red to speak, but not turning his attention away either. Red would talk when he was ready and never before that.  
  
"okay, y'know how a good number of monsters from the Snowdin and Waterfall regions wear or were wearing collars when we came out?" Red asked, not meeting Sans' eyelights. Sans made a sound of acknowledgement. "there's... a reason for it. back underground, it was a promise. ta protect what's yers. a vow to keep the collared monster safe and happy, and ta exact revenge on anyone that dared mess with the collared monster. ta accept and wear the collar is a sign of trust, that yer accepting the feelings of the one ta make and give ya the collar..." Red sighed, fiddling with the hem of his jacket sleeve. "sorry i never told ya before."  
  
Sans grinned as he listened to Red speak, though considering the fell monster wasn't looking at him, he never saw that Sans wasn't in the least bit surprised by what he was being told. Sans chuckled, causing Red to look up at him sharply. "i was wondering when you were going to get around to telling me that," he said, amusement in his tone.  
  
"how...?"  
  
"how'd i know? not long after you gave it to me... remember how Edge came for that surprise visit? i was still wearing the collar when he showed up, before it really became an important ritual in our play. he explained it to me when i told him you gave it to me," Sans said, snickering.  
  
"...ya knew... all this time? and ya still...?" Red asked, shocked. Sans nodded.  
  
"to be honest, i was pretty happy that you cared enough about me to make a promise like that, even if you never told me anything," he replied, voice gentling. "i already knew i loved you by that point, and even though it didn't necessarily mean you returned my feelings the way i really wanted, it still meant that i was important enough to you that you wanted to protect me. i probably made the dopiest happy face upon finding out, because Edge... well... you should have seen my text history with him after that. he really cares about you, y'know?"  
  
"...yeah. fuck, sans, we could'a been in a real relationship fer so long and both'a us were afraid ta ruin what we already had," Red said with a soft, fond laugh.  
  
"...i should have known better. we're two sides of the same coin, after all," Sans returned, sighing and leaning into Red, nuzzling his collarbone happily. "i'm glad i confessed, even though i don't really remember doing so."  
  
Red snorted. "man, ya were so deep in subspace at that point that i'm surprised ya even vaguely remember confessing. but i'm glad ya did, too. otherwise, we'd probably still be beating around that bush even now," he said with a laugh. This time it was Sans' turn to snort.  
  
"unlikely. i think your bro was probably right on the verge of shoving us in a closet together and not letting us out until we'd both confessed," he said with a laugh. Red snickered at that, not denying that that was probably what would have happened had they not started dating.  
  
They both got a good chuckle out of it before Red sobered, looking away again. "so, uh... there's a reason i told ya that. direct collaring, as i'm sure ye've noticed, has fallen a bit outta style with most fell monsters. i guess a bit of class has rubbed off on us from our nicer alternates, so only the wolf pack and more animal-based monsters are still doin' it. i, uh... still want ya ta wear my collar when we play, but... i made ya somethin' else..."  
  
Sans canted his head, watching as Red fumbled a little bit, pulling a velvet jewelry box from his phone inventory space, handing it to Sans wordlessly. Sans opened it. Inside was a short braided leather cord and a pendant. The cord itself was unremarkable, just tightly braided black leather, though it was soft and supple to the touch. The pendant on the other hand... It was made of a small piece of glittering crystal, a spark of red magic contained within, making it shine softly. It looked to have been painstakingly cut into the shape of a four-pointed star, the uppermost point encased in a silver setting to dangle from the cord.  
  
When Sans looked up with widened sockets, he could see Red looking away with a deep flush. "this... carries the same meaning as the collar?" he asked softly. Red nodded, and Sans smiled softly. "help me put it on?" he asked, and Red looked up sharply, only to smile helplessly at the look on Sans' face as he held out the accessory for Red to take.  
  
"sure, sweetheart."

**Notes for the Chapter:**

> missing tag; "Edge is best meddling brother who only wants Red to be happy"


	2. Chapter 2

**Notes for the Chapter:**

> supposed to be working on a 12 Days prompt? get hit with a mini-plot bunny that bites instead. sorry.

"hey, red?" Red looked up from the paper he'd been idling scribbling on as he waited for Sans to get home. His eyelights landed first on the glittering star hanging from Sans' neck, gaze softening abruptly as he enjoyed how Sans so proudly displayed his gift. Finally, he met Sans' gaze, noting the soft blue flush on his partner's face. Curious, he turned completely to Sans, canting his head a little.  
  
"yeah? what's up, sweetheart?" he asked gently.  
  
"i, uh... was talking to wolfami and wolfaressa a while back, and, uh... y'know how they collared each other?" Sans asked, nervousness causing magic to bead on Sans' skull.  
  
"well, yeah. they wanted ta make certain everyone knew that they had each other's backs," Red replied, arching a browridge.  
  
"um... they told me.... that wasn't the only reason." Sans paused, pulling out a velvet box similar to the one Red had presented Sans with the previous year. "we've been together for a long time, and... while i'm happy with how things are now, i, uh... i want something more. i don't want to just be your boyfriend anymore, red."  
  
Red blinked slowly, taking the box being offered to him and opening it. Inside was a star pendant made as close to identical as possible to the one Sans wore. The biggest difference was the pale blue magic sparkling at the core of the star. "sans... are ya... asking ta soulbond with me?" Red asked softly, a note of awe in his tone. There'd always been that small niggling of doubt in the back of his mind that Sans would get tired of him like Boss clearly had and leave him, but this blew that doubt away. No one popped that sort of proposal without being deadly serious. Not even in his own universe had soulbonding been treated as any kind of joke.  
  
"y-yeah. that's exactly what i'm asking," Sans replied quietly, shifting from foot to foot in nerves. Red quietly pulled the pendant, cool with Sans' magic, from the box before aiming the widest, happiest smile he'd ever worn at Sans.  
  
"help me put it on?" The returned words from the year previous caused a matching smile to blossom on Sans' face.


End file.
